* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    overflow: hidden;
    font-family: Arial, sans-serif;
}

body, html {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  font-family: sans-serif;
}

#header {
    display: flex;
    justify-content: center;
    background: rgba(255,255,255,0.8);
}

h1 {
    font-size: 40px;
    text-align: center;
    color: rgb(40, 55, 40);
}

#btn-container {
  display: flex;
  justify-content: center;
  display: flex;
  margin-top: 100px;
  gap: 15px;
}

#btn {
  padding: 10px 20px;
  border: none;
  background: rgba(255,255,255,0.8);
  border-radius: 8px;
  cursor: pointer;
  font-size: 16px;
}

#btn:hover {
    background: rgba(255,255,255,1);
}

a {
    text-decoration: none;
    font-size: 25px;
    color: black;
    font-weight: bolder;
}

#myVideo {
    position: fixed;
    top: 0;
    right: 0;
    min-width: 100%;
    min-height: 100%;
    z-index: -1;
}



@media (max-width: 768px) {

    #container-countdown {
        padding-top: 8vh;
    }

    #btn-container {
        margin-top: 6vh;
    }
}



@media (max-width: 480px) {

    #countdown {
        border-radius: 14px;

        line-height: 1.3;
    }

    #btn-container {
        flex-direction: column;

        align-items: center;

        gap: 12px;
    }

    #ButtonStart,
    #ButtonStop {
        width: 80%;
    }
}